If you want to disable “Continue with this logon without ending any other logons in system…”option while trying to logon SAP system for your users then you have activate “login/disable_multi_gui_login” parameter.
You can find the standart logon options screen below ;

“login/disable_multi_gui_login” parameter’s value : 0

Let me show you other SAP system’s related parameters output ;

“login/disable_multi_gui_login” parameter’s value : 1

And after activating the parameter the logon screen selections are like below